// Array.prototype.includes
const arr = ['foo', 1, NaN, false];

console.log(arr.indexOf('foo'));
// 打印-1，因为indexOf识别不了NaN
console.log(arr.indexOf(NaN));

console.log(arr.includes(NaN));

// -========指数运算
console.log(Math.pow(2, 10));
console.log(2 ** 10);
